In reverberant environments, e.g. rooms with hard surfaces, churches, etc., the ability to understand speech declines. This is so because the signal from the target speaker is reflected on the surfaces of the environment; consequently, not only the direct (un-reflected) sound from the target speaker reaches the ears of a user, but also delayed and dampened versions are received due to the reflections. The “harder” a room is, the more reflections.
EP1469703A2 deals with a method of processing an acoustic input signal into an output signal in a hearing instrument. A gain is calculated using a room impulse attenuation value being a measure of a maximum negative slope of the converted input signal power on a logarithmic scale.